1. Field of the Invention
The present invention relates to a traffic information generating apparatus and a traffic information generating method for generating traffic information including congestion information. In particular, the present invention relates to a traffic information generating apparatus and a traffic information generating method for generating traffic information, based on probe information collected from a navigation apparatus installed in a probe car.
2. Description of the Related Art
In recent years, various types of traffic information generating apparatus and traffic information generating methods have been proposed which use a traveling vehicle as a sensor (“probe car”) and which generate traffic information including congestion information based on probe information, such as speed (time/location), that has been collected from the probe car.
For example, depending on the circumstances of collection of the probe information, i.e., for example, depending on the number of probe cars traveling a given road section that is a target for the collection of information and further depending on the driving speeds of the probe cars, the road length, i.e. the length of a traffic information judging section, used for judging the road conditions including the level of traffic congestion, can be variably set. Traffic information generating routes, defined by vehicular traveled route data, are divided into the variable traffic information judging sections, so that traffic information including an average travel time, the level of congestion, and an average speed is obtained for each judging section. One example of a traffic information generating apparatus and a traffic information generating method is disclosed in Japanese Patent Application Publication No. JP-A-2006-31422; (paragraphs 0022 to 0064 and FIGS. 1 to 12) wherein, when the number of probe cars is small or when the driving speed of the probe cars is high, the judging sections are longer, whereas when the number of probe cars is large or when the driving speed of the probe cars is low, the judging sections are shorter.